The field of art to which this invention pertains is water reducible coating compositions made from aqueous dispersions of epoxy resins blended with the reaction product of epoxy resins and polyoxyalkylene polyols terminated with phosphoric acid.
In view of the air pollution caused by organic solvents and to the increasing scarcity and cost of hydrocarbon solvents, there is a continuing search for new and improved coating compositions which can be dissolved or dispersed in water.
Water-borne coatings are being investigated for use in coating metal substrates which after being coated are formed into various objects, e.g., bottle caps, screw caps and can ends. The coatings for such applications must be capable of being deep drawn, must be flexible and must have good adhesion properties.
Water-borne coating compositions capable of being used on flexible substrates are described in commonly assigned U.S. Pat. No. 4,360,613. Such compositions are made from the reaction product of epoxy resins, polyoxyalkylene polyols and phosphoric acid blended with aminoplast resins. Although suitable for flexible substrates, such as aluminum foil and paper board, such coating compositions cannot be deep drawn on metal substrates without some coating failures.